A newly isolated mutation has helped a species of bottom-feeding fish called the tomcod survive Hudson River pollution.
The mutation is naturally occurring, but Dr. Isaac Wirgin, of NYU, said it's what protects the tomcod from toxic PCBs.
"If it didn't exist, they probably wouldn't survive because the levels of exposures that they have and the amount they accumulate would be sufficiently high to kill them," Wirgin said.
Wirgin's findings are published in the latest issue of the journal Science.
"When you're thinking of evolution, you're thinking of tens of thousands to millions of of years," Wirgin said. "And here, we're talking about probably under 100 years. That's telling you that selective pressure must have been enormous."
The ability of some organisms to evolve fairly quickly is well-established. But Wirgin says it's a breakthrough to locate the exact gene where the mutation is located in an organism as complex as a fish -- and to work out the exact way it protects the tomcod from PCBs.
Elsewhere, the mutation is found in five percent of tomcod, but in the Hudson, it's found in 100 percent of them.
The mutation effectively protects cells in the fish from the PCBs, even as it accumulates the toxin in its liver.
Wirgin said few people eat tomcod, but they're an important prey fish for other, larger species of fish. That means the tomcod brings the PCBs up the food chain -- including to some fish that anglers catch recreationally and eat.